Resistivity modulation of perovskite samarium nickelate with high-valence cations and the underlying mechanism

The critical role of H2 reduction roasting for enhancing the recycling of spent Li-ion battery cathodes in the subsequent neutral water electrolysis

“…It was noted that the (003) diffraction peak shifted toward higher 2 θ after leaching at 60 °C and 80 °C compared with that after leaching at 25 °C and 40 °C, likely due to the migration of Ni 2+ to the Li + layer. Ni 2+ (0.069 nm) 46 and Li + (0.076 nm) 47 have similar radii. Since Ni 2+ has one more positive charge than Li + , when the Ni 2+ occupied the vacancies created by the removal of Li + , the electrostatic attraction between Ni–O reduced the distance between metal–oxygen octahedral layers, resulting in the decrease of the lattice parameter in the c -axis direction, 48 so the (003) diffraction peak shifted toward higher 2 θ .…”